LIGHT-EMITTING DEVICE

PURPOSE:To provide a light-emitting device in which stable control for a constant light output can be performed. CONSTITUTION:Since a wavelength selecting filter 80 is provided in the front face of the light-receiving surface of a light-receiving element 50, only emitted light from the light-emitting element selectively passes through the wavelength selecting filter 80 to be incident upon the light-receiving element 50. When the disturbance light of wavelength different from the wavelength of the emitted light enters a package 60, the disturbance light is cut off by the wavelength selecting filter 80, and therefore it is not incident upon the light-receiving element 50. Accordingly, since almost all of of the disturbance light which enters the package 60 are not incident upon the light-receiving element 50, almost normal control for a constant light output can be performed even when the disturbance light enters the package 60.